1. Field of the Invention
The present invention relates to a rotating blade and an air foil, and more particularly, to a rotating blade and an air foil rotated or lifted by a flow of fluid.
2. Background Art
Wind energy has been used as a source of mechanical power for a long time. Wind power generated by a flow of wind is transmitted to a blade as wind collides with a collision face of the blade, and the wind energy is converted into a mechanical energy while the blade rotates by the wind power. Such a mechanical energy may be converted into an electric energy through a turbine, and in this instance, a conversion efficiency is crucial to the energy conversion.
In order to obtain a great deal of electric energy from the same amount of mechanical energy, it is preferable that the blade has a high energy conversion efficiency. That is, when the initial wind energy is converted into a mechanical energy through the blade, the amount of the mechanical energy obtainable from wind energy of the same power varies according to shapes (or structures) of blades, and the energy conversion efficiency shall be determined according to the amount of obtainable energy.
Meanwhile, when wind flows along the upper face and the lower face of an air foil, a lifting force substantially vertical to a wind flow direction, whereby the lifting force is applied on the air foil. The lifting force can lift the air foil up from the ground. That is, wind power is converted into lifting force, and as described above, in case of the high energy conversion efficiency, a great deal of lifting force can be obtained from wind power of the same power.